Synopsis

Groundwater that is abstracted for human consumption from shallow, sandy ground can hold traces of pollutants and microorganisms from human and animal sources. This can be concluded from a field study carried out by the National Institute for Public Health and the Environment (RIVM) at four of these possibly vulnerable abstraction sites. However, compared to previous international studies, the levels of viruses and bacteria found in the Netherlands were much lower than expected. The drinking water that is produced cannot be tested for its compliance with the quality standards for viruses and bacteria on these results alone. The permitted level of pathogenic viruses and bacteria in drinking water is so low that direct analysis is not possible. The microbiological safety of drinking water is therefore for several years now, determined by a risk-assessment (VROM-Directive 5318) covered by legislation. In order to gain more information on the microbiological quality of drinking water, the RIVM recommends a further refinement of this risk assessment method for groundwater abstractions that could be considered vulnerable. The present report can act as a guide for this procedure. Using groundwater for the production of drinking water is an attractive choice, compared to surface water, because the water in the soil is more or less protected from pollutants at ground level. Moreover, the concentrations of substances and microorganisms that do still reach the groundwater will be flattened and to a certain extent removed. In addition, protection zones around abstraction sites have been set to further reduce the risk of pollution at ground level. In this respect, a total ban on all activities not directly related to drinking water production is being enforced within the water collection area. The results of this field study do not indicate that the size of the water collection areas should be adjusted in national groundwater protection policy.